In particular in the case of off-road vehicles, such as construction machines and tractors, the vehicle seat greatly influences the driving comfort. Excessive vibrations, jolts and movements that are transmitted from the road surface via the vehicle seat to the person located on the seat can lead to fatigue and in the longer term also to an adverse effect on health, such as, for example, back pain or bone erosion, of the person. Damping/suspension systems are generally used to minimise influences of this type. For this purpose, various suspension variants are known in principle, which differ with respect to complexity and energy requirement: passive, semi-active and active suspension systems. In the case of passive vehicle seats, the properties of the system components are structurally predetermined and cannot be changed during operation. In the case of semi-active suspension systems, the dissipative properties of the seat suspension can be influenced in a targeted manner depending on the respective situation. Either the hardness of the damper can be adjusted and/or the stiffness of the spring can be adapted. In active systems, energy can additionally be introduced into the system by suitable actuators.
Damping/suspension systems of this type generally have a maximum damping/spring travel. For an off-road journey, the forces acting on the vehicle or the vehicle seat may be so great that the damping/suspension system undergoes large deflections. Owing to the finite mechanical limitations of the conventional damping/suspension systems, large forces acting on the seat can bring about an end impact of the damping/suspension system. Different damper systems are known in order to avoid end impacts of this type. For example, passive dampers having a spring travel-dependent or suspension speed-dependent damping force are known. Furthermore, actively or semi-actively adjustable damper technologies are known in the prior art. Adjustable damper technologies are based, for example, on electro-/magneto-rheological systems or on an electrically or mechanically controlled through-flow change of the damper. Known algorithms for the active adjustment of the damping are, for example, the Skyhook rebound control or the Huang adjustment algorithm.
A pure speed-dependent passive or adjusted damper does not utilise the spring travel still available, which, on the one hand, could be utilised or is no longer present. This type of damper is designed either for the worst case, in which each impact is avoided in each possible seat setting, or for an adequate spring travel. In the first case, the setting is generally felt to be too hard and, in the second case, unpleasant impacts cannot be avoided in the edge positions. Travel-dependent passive dampers, at the end of the spring travel, provide a harder damping, but this damping is also inefficiently and unpleasantly active when springing back, wherein adequate spring travel is again present.
A damping adjustment should moreover also allow a user-specific damper presetting.